I am missing several months of bank activity. How do I import the missing transactions? I have tried importing them via a CSV file but I get an error message

Try using csv2qbo converter tool as a workaround.

https://www.moneythumb.com/?ref=110

I appreciate your proactive effort in uploading the missing entries using a CSV file, Imperial. Let’s review the document to ensure it’s properly formatted for a smooth import into your account.

Beforehand, may I know what specific error message you’ve encountered when uploading these transactions? Any additional details would be much appreciated.

When managing online entries, most banks let you download transactions from their website into a CSV file. Importing this document to QuickBooks requires the 3-column and 4-column formats to allow entries to be uploaded. I’m including this screenshot for reference.

Once you're ready, manually import your file and consider narrowing the date range and splitting larger uploads into smaller batches to optimize the importing process. You can also refer to this guide to rectify specific issues: Fix bank upload errors.

I’ll leave this thread available so you can always reply below for any additional queries.